When a pipe installer installs a natural gas service to a house or other building, the service must be checked for leakage, before connecting the service into the main. Various devices are available on the market for accomplishing this testing, but most utilize simple gauges which are used, after the service line has been filled with a gaseous material under pressure, to show directly any drop in pressure in the service line. However, for very small leakages, which none-the-less could be very dangerous over a long period of time, the amount of leakage is often so small that it cannot be detected on a normal pressure gauge.
It is therefore desirable to be able to provide a system which is more sensitive to small leakages.